Regarding Pulvigera/Orthotrichum lyellii in the Pacific Northwest

One of the most common epiphytic mosses in the PNW is something that was traditionally called Orthotrichum lyellii. It immediately announces itself on account of its longish, erectish, unbranched-ish shoots, short sporophytes with hairy caps. When a group of bryologists in Spain took a closer look at herbarium samples of purported O. lyellii, they found collections from western North America were distinct.

The type specimen of Orthotrichum lyellii seems to have been collected on a tree in the "New Forest, Hants" (present day southern England) by a young Charles Lyell long before the publication of his three volume Principles of Geology. The material was treated as a new species by WIlliam Jackson Hooker (First Director of Kew Gardens, father of Joseph Dalton Hooker) and Thomas Taylor in their Muscologia Brittanica. It is notable for having seperate male and female plants ("Dioicous") and little asexual propagules on the leaves.

The problem that Lara et al. addressed was that the material from the west coast of North America, while having seperate male and female plants, lacked those asexual propagules on the leaves. They expanded on the concept of the genus Pulvigera to include all dioicous species previously treated as Orthotrichum. After some molecular work and morphological characterization, it turned out that Orthotrichum lyellii does not occur in the Pacific Northwest, with the closest records being in California. That material, with its asexual propagules is now referred to as Pulvigera lyellii.

What does occur in Oregon, Washington and British Columbia turned out to be two morphologically distinct species: Pulvigera pringlei and Pulvigera papillosa. Below I copy and paste the couplet from Lara et al.'s revised key to the genus. That in turn is followed by links to examples of iNat observations of these species. While some of the characters are microscopic, the size and form of the sporophyte is something that can be seen in the field and caught on film.

Vaginula densely hairy; capsules emergent to short exserted, seta 1.75–3.40 mm long; operculum plane
or slightly plane-convex, with a broad reddish-orange basal rim; external side of teeth with papillae and
longitudinal lines in the upper part; endostome with a faint connective membrane, no or faintly coloured;
spores finely papillose .......................................................................................................................P. pringlei
Vaginula sparsely hairy; capsules almost immersed to widely emergent, seta 1.0–1.5 mm long; operculum
strongly convex, almost dome-shaped, rarely plane-convex, with a little conspicuous yellowish to pale
orange basal rim; external side of teeth coarsely papillose in the upper part; endostome with a showy
orange connective membrane; spores coarsely papillose ............................................................. P. papillosa

Example of Pulvigera pringlei. -note long seta
Example of Pulvigera papillosa -note short seta and nearly immersed capsule, convex operculum
Example of male plant of Pulvigera, which cannot be IDed to species unless growing in close proximity to a female plant bearing sporophytes. Note bulb-like growths where antheridia (sperm-beaaring organs) are engulfed in leaves
Example of actual Pulvigera lyellii -- note the abundant asexual propagules growing on the leaf surface

Posted on Δεκέμβριος 31, 2022 0201 ΠΜ by rambryum